W. B. No. 579. 

iGB 1205 

U6 
11916 
Copy 1 



U. S. DEPARTAIENT OF AGRICULTURE, 

WEATHER BUREAU. 
CHARLES F. MARVIN, Chief. 



INSTRUCTIONS TO 

SPECIAL RIVER AND RAINFALL 
OBSERVERS. 



BY 



ALFRED J. HENRY, 

Professor of Meteorology, 




WASHINGTON: 

GOVERNMENT PRINTING OPPIOE. 

161& 



W. B. No. 579 



U. S. DEPARTiMENT OF AGRICULTURE, 

WEATHER BUREAU. 

CHARLES F. MARVIN, Chief. 



INSTRUCTIONS TO 

SPECIAL RIVER AND RAINFALL 
OBSERVERS. 



BY 



ALFRED J. HENRY, 

Professor of Meteorology, 




WASHINGTON: 

GOVERNMENT PRINTING OFPIOE. 

1£1& 






D. of D. 
JUL 15 1916 



^ 



?x 



4c 



NOTE TO OFFICIALS IN CHARGE OF DISTRICT CENTERS. 

In general the instructions for Weather Bureau officials in charge 
of river district centers will be found in Station Regulations. There 
has been included in this pamphlet, however, some matter that is 
closely related to the work of the district center, yet is scarcely 
appropriate to Station Regulations, as, for example, the paragraphs 
on rain gage and on river gages in general. 

Special attention is directed to the insert sheets at the end of the 
pamphlet. These sheets are designed to carry the specific instruc- 
tions from the district center to the river or rainfall observer as to 
when to use the telegraph, etc. It is expected that each district cen- 
ter will complete a set of insert sheets for every river or rainfall 
o])server in his district and attach the sheets to the gummed stubs at 
the end of the pamphlet. A duplicate set, should be retained at the 
district center and additional specific instructions may be added 
from time to time by forwarding new insert sheets. 

NOTE TO RIVER AND RAINFALL OBSERVERS. 

This book of instructions will be carefully preserved. When an 
observer is relieved he will turn it over to his successor, obtaining 
the latter's receipt therefor, which will be forwarded by mail to the 
official in charge of the district. 



•#. 



LIST OF ILLUSTRATIONS. 



1. An 8-inch rain gage. 

2. Rain gage and box support 

3. Vertical staff gage. 

4. Inclined river gage. 

5. Vertical gage painted on a bridge pier. 

6. Enameled scale gage. 

7. Chain and weight gage, short box pattern. 



INSTRUCTIONS 

FOB 

SPECIAL RIVER AND RAINFALL OBSERVERS. 



OBJECT OF RIVER AND RAINFALL OBSERVATIONS. 

The river and rainfall stations of the Weather Bureau are main- 
tained primarily for the purpose of giving warning of the approach, 
magnitude, and duration of high waters, and for forecasting water 
stages at all heights, in the interest of navigation on the inland water- 
ways of the country. The river and precipitation data are also of 
great value to various other interests, particularly to those concerned 
with the problems of irrigation and water supply. 

DISTRICT CENTERS. 

For the better supervision and control of the work, the special 
stations are arranged in districts. These districts are under the direc- 
tion of officials at regular meteorological stations of the Weather 
Bureau, designated as district centers. 

All correspondence relating to the work of substations, such as the 
furnishing of supplies, renewal of gages, settlement of accounts, and 
employment of observers, should be conducted through the official in 
charge at the district center to which the station is assigned. In the 
case of a combined station the official in charge of the river district 
will communicate direct with the station on matters connected with 
river work, but he will furnish copies of all important correspondence 
to the section director or other official who is also concerned in the 
work of the combined station. 

Persons accepting positions as special river and rainfall observers of 
the Weather Bureau become authorized agents of the United States, and 
are amenable to the laws in case of neglect of duty. 

Records of river stages. — The records of stages are preserved at 
Washington and printed from time to time. They are accessible at 
Washington, D. C, river district centers, and at Weather Bureau 
stations in the larger cities. 

SUPPLIES. 

Supplies of blank forms, franked and addressed envelopes, rain 
gages, measuring sticks, and other necessary supplies are furnished 

7 



8 llsrSTRUCTIONS TO SPECIAL RIVER AND RAINFALL OBSERVERS. 

to observers upon application to the official in* charge of the district 
center. Timely requisition will be made for such supplies as are 
needed, and the needs of the station must be so anticipated as to 
allow ample time for the delivery of the articles from the central 
office at Washington, D. C, through the district center. One month 
is usually sufficient for this. 

PROPERTY. 

If the river gage is the property of the Weather Bureau, it is 
under the direct care of the river observer, but it will not be repaired 
or changed in any manner without the consent of the official in charge 
of the river distict. 

Advise the district center whenever the gage needs repairs. It is 
important that the gage be kept in good repair and well painted. 

Advise the district center promptlj^, by telegraph, if serious, of 
any damage to the gage that affects the accuracy of the readings. 

If the gage is not the property of the Weather Bureau, it is im- 
portant that the observer inform the district center of any repairs or 
changes made or when repairs are necessary. 

When property and supplies are furnished to an observer, an item- 
ized receipt therefor will be immediately mailed to the official in 
charge of the district. 

When an observer is relieved from charge of a station, he will 
make out a list in triplicate of all Government property in his pos- 
session, and append at the bottom thereof the following certificate : 

(Date) , 19—. 

I certify that I have this day received from (name of former 

observer) the above-rogntioned articles in good condition unless othervi^ise speci- 
fleld hereon. 

(Name of new observer) . 

One copy of this report will be mailed to the official in charge of 
the district, one given to the new observer, and the third retained by 
the retiring observer. 

When from any cause any article of property becomes unservice- 
able or in need of repairs, the fact must be at once communicated to 
the official in charge of the district, for such action as he may deem 
proper and necessary. 

INSTRUCTIONS. 

The duties of a river observer consist in noting on a form furnished 
for the purpose — 

(1) The height of water on the gage, with change in 24 hours. 

(2) Depth of rain or melted snow, with times of beginning and 
ending. 



INSTRUCTIONS TO SPECIAL RIVER AND RAINFALL OBSERVERS.^ 9 

(3) Actual depth of snow, if any, since last observation. 

(4) Direction of wind. 

(5) State of weather. 

(6) Depth of snow, if any, on ground on 15th and last day of 
month ; also date on which last snow of season disappeared. 

(7) Stage of river at crest of each flood, with hour of day, should 
it not occur at time of regular observation. 

Detailed instructions as to the manner of keeping the records of 
river stages and the weather will be found on the back of Form No. 
1006-Met'l. 

A postal card — Form 1049-Met'l — must be carried to the river 
gage and the readings entered thereon as soon as made. On the last 
day of the month this card, which is the original record of the daily 
stages of water in the river, will be mailed to the district center, 
except that the following stations will forward the form to the cen- 
tral office at Washington : Keokuk, St. Louis, Memphis, Vicksburg, 
New Orleans, Cincinnati, Cairo, Nashville, Johnsonville, Kansas 
City, Little Rock, and Shreveport. 

Telegraphic reports are also made under certain special conditions, 
as hereinafter described. 

Rainfall ohservers. — The duties of a rainfall observer consist in 
noting on a form furnished for the purpose — 

(1) The depth of rain or melted snow, with times of beginning and 
ending. 

(2) Actual depth of snow, if any, since last observation. 

(3) Direction of wind. 

(4) State of weather. 

(5) Depth of snow, if any, on ground on 16th and last day of 
month. 

Telegraphic reports are also made under certain conditions, as 
hereinafter set forth. (See insert page at end of pamphlet.) 

FORMS FOR RECORDING OBSERVATIONS. 

Form 1006^ MetU, — The record of the observations made at the 
station for the month should be filled up in accordance with the 
instructions printed on the back of the form. 

The form should be mailed to the official in charge of the district 
center on the first day of the succeeding month. 

Before mailing, a copy must be made by the observer in the book 
furnished for that purpose. 

At stations supplied with books of Form 1006, Met'l, on thin 

(onion-skin) paper, three copies of the form will be prepared. The 

first two or top copies of the form will be mailed to the district 

center and the last copy will be left in the book and will constitute 

39509—16 2 



10 INSTRUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 

the retained record of the river station. (Four or five copies can be 
prepared by using a hard indelible lead pencil, if special conditions 
at a station should require more than three.) 

The descriptive data at the head of Form 1006-Met'l will be care- 
fully entered each month and will be verified at the district center; 
particuliir care being taken to see that the name of the station, 
month, and year, and name of the observer are properly entered. 
Means will not be computed for less than 15 days. 

Form SO^Jf^ Tel. — For telegraphing reports in accordance with 
instructions hereinafter given. 

Form 108i^ Mefl {postal card) . — For reporting the daily observa- 
tions to the official in charge of district center or to other officials 
when required. 

TELEGRAPHIC REPORTS. 

As a general rule, whether or not river stages will be telegraphed 
to the district center daily depends on the value of the reports, 
either for the purpose of issuing flood warnings or in the interests 
of navigation. Instructions as to when the telegraph or telephone 
shall be used will be found on the insert sheets at the end of this 
pamphlet. 

In telegraphing a report of heavy precipitation to the district 
center the telegram should be sent immediately when the heavy rain 
ceases. Do not wait until the time of the regular daily telegram. 
At stations telegraphing daily the morning telegram should include 
the total 24-hour rainfall, although a part of it may have been re- 
ported in a special observation. 

Telegraphic reports will contain the fullest information possible 
within a limit of 20 words, including the address and signature. 

Reports for telegraphic transmission will be written on Form 
3024 Tel., in the following order: First, the word "observer"; sec- 
ond, name of the place to which the report is to be telegraphed; 
third, name of station from which report is telegraphed ; fourth, time 
of observation, if other than the time of the regular morning ohserva- 
tion; fifth, stage of river ; sixth, tendency of river, as " rising," 
" falling," " stationary," as the case may be ; seventh, state of 
weather, " clear," "partly cloudy," " cloudy," " raining," " sleeting," 
" snowing " ; eighth, depth of rainfall ; ninth, depth of unmelted 
snow, in inches (in case of no precipitation, add the word "none") ; 
tenth, special remarks, such as "floating ice," "heavy loss of crops 
and stock," " frozen," or any other information of value ; eleventh, 
surname of the observer. 

Reports of regular morning observations should not contain the 
time word in the telegram. 



INSTRUCTIONS TO SPECIAL EIVEEAND RAINFALL OBSERVERS. 11 

The direction of the wind will not be sent, unless specially called 
for by the official in charge of the district center. 

The rising or falling tendency of the water should indicate the 
condition at the actual time of the observation and not with reference 
to the preceding observation. For instance, the river may have been 
rising for several days and it may be higher than at any preceding 
regular observation, but it may have started to fall. In such an 
event telegraph " falling." 

The reports should be carefully and legibly written in letters that 
can not be misunderstood. Observers are advised to write messages, 
whenever possible, in print letters instead of a running hand. The 
actual stage of the river in feet and tenths of a foot will be spelled 
out, as " twenty- four feet six," " twenty-two feet," etc. ; the rainfall 
in inches and hundredths of an inch will be spelled out, as " one 
inch twenty-two," " three inches five," etc. The word " rising " or 
"falling," coming between the stage of water and the amount of 
rainfall, will prevent mistakes by confusing the tenths of a foot with 
the inches of rainfall. When less than 1 inch of rainfall is to be 
reported, the word " hundredths " should be added, as " seventy-four 
hundredths," " six hundredths," etc. 

Messages should be filed at the telegraph office as soon as prac- 
ticable after the observation has been taken. One copy of the tele- 
gram will be given to the operator at the telegraph office and one 
copy retained by the observer. 

The following are examples of telegraphic reports : 

1. Telegram from an observer who reports each morning by tele- 
graph : 

Hermann, Mo., March 1, 1015. 
Obseever, St. Louis, Mo.: 
Hermann, sixteen feet three stationary clear none. 

Jones. 
[Translation.] 

Observer, St. Louis, Mo Address of Weather Bureau observer at St. Louis, Mo. 

Hermann Name of river station at Hermann, Mo. 

Sixteen feet three Stage of river, 16.3 feet. 

Stationary River stationary at time of observation. 

Clear State of the weather. 

None No precipitation. 

Jones Surname of river observer. 

2. Telegram from an observer taken at a time other than the regu- 
lar morning observation hour : 

April 30. 1914. 
Observer, Memphis, Tenn.: 
Helena two p. m. minus two feet eight falling clear none. 

Brown. 



12 INSTRUCTIONS TO SPECIAL KIVER AND RAINFALL OBSERVERS. 

[Translation.] 

Observer, Memphis, Tenn Address Weather Bureau observer at Memphis, 

Tenn. 

Helena Name of river station at Helena, Ark. 

Two p. ra Time of observation, 2 p. m. 

Minus two feet eight Stage of river, —2.8 feet, or 2.8 feet below the 

zero mark on the gage. 

Falling River falling at time of observation. 

Clear State of weather. 

None No precipitation. 

Brown Name of river observer. 

3. Telegram containing regular morning observation, with infor- 
mation as to crest of flood : 

March 20, 1914. 
Obspjrver, Memphis, Tenn.: 

Helena forty one feet two cloudy one inch two highest forty one feet six 
about 8 p. m. 

Brown. 
[Translation.] 

Observer, Memphis, Tenn Address Weather Bureau observer at Memphis, 

Tenn. 

Helena Name of river station at Helena, Ark. 

Forty one feet two Stage of river, 41.2 feet. 

Cloudy State of weather. 

One inch two Precipitation, 1.02 inches. 

Highest forty one feet six Crest of flood, 41.6 feet. 

About 8 p. m Crest occurred about 8 p. m. 

Brown Name of observer. 

4. Telegram from an observer who does not send daily observations 
by telegraph: 

April 3, 1915. 
Observer, Cincinnati, Ohio: 

Charleston 10 a. m. twenty nine feet three rising rapidly snowing thirty two 
hundredths ice gorge half mile below. 

Jones. 

[Translation.] 

Observation taken at 10 a. m. 
Stage of river, 29.3 feet ; rising rapidly. 
Snowing; precipitation, 0.32 inch. 
Ice gorge half mile below. 
Jones, river observer. 

5. Telegram from an observer who does not send daily observations 
by telegraph : 

April 7, 1915. 

Observer, Pittshurgh, Pa.: 

Sharon 8 a. m. nine feet two rising rapidly raining two inches twelve bottoms 
beginning to flood. 

Brown. 



INSTKUCTIONS TO SPECIAL EIVER AND BAINFALL OBSERVEES. 13 

[Translation.] 

Observation taken at 8 a. m. 
Stage of river 9.2 feet ; rising rapidly. 
Raining; precipitation 2.12 inches. 
River bottoms beginning to flood. 

Special observations. — Special observations will be made in ac- 
cordance with the instructions on the insert sheets in the back of this 
pamphlet. They will be prepared according to the instructions on 
page 12, examples 4 and 5. 

A statement of all observations telegraphed will be entered on 
Form 1006, under "remarks," giving the day and the hour taken. 
Failure to record extra observations or the fact that observations 
were telegraphed for which compensation is claimed will necessitate 
suspending payment until the discrepancies are explained. 

With each important rise it is desired to have a special observa- 
tion at the time of the highest water. If this can not be done, but the 
highest point reached by the river can be determined, it is desired 
that this be entered on Form 1006, giving the approximate time it 
occurred. In case the exact time of crest is not known, always enter 
"Approximately " after the time given. 

Observations missed. — Eegular morning observations missed will 
be deducted from the pay roll unless satisfactorily explained. The 
Chief of the Weather Bureau reserves the right to withhold pay- 
ment from any person who persistently neglects to make his reports 
accurately and forward them promptly. Payment will be made 
quarterly. 

Observations should, when possible, have substitutes capable of 
performing all the duties of a river observer in order that there may 
be no interruption of the work in case of sickness or unavoidable 
absence from the station on the part of the regular observer. Mem- 
bers of the observers' families are very often instructed in the work. 

RAIN GAGE. 

EXPOSURE OF RAIN GAGE. 

The exposure of the rain gage is a very important matter. The 
most serious disturbing effecting in collecting rainfall is the wind. 
In blowing against the gage the eddies of wind formed at the top 
and about the mouth of the gage carry the rain away, so that too 
little is caught. 

Observers will take particular care in selecting a good place for the 
location of a gage, as the value of the records is sometimes greatly 



14 INSTRUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 

impaired by improper exposure. It is scarcely necessary to say that 
every precaution should be taken to protect gages from the interfer- 
ence of animals and unauthorized persons. Select, if possible, a 
position in some open lot as unobstructed as possible by trees, build- 
ings, or fences. Such a place, in general, affords the best exposure. 

INSTRUCTIONS FOR THE USE OF THE RAIN GAGE. 

Description of gage. — The rain gage consists of the following 
parts: The receiver A; the overflow attachment B; the measuring 
tube C, 

The top cylindrical portion of the receiver, marked «, see figure 1, is 
exactly 8 inches in diameter inside and is provided with a funnel- 
shaped bottom which conducts any precipitation falling into the 
receiver into the tall cylindrical measuring tube C^ the total height of 
which, inside, is exactly 20 inches. The diameter of this tube is much 
smaller than the large receiving tube a, being only 2.53 inches. In 
consequence of this a small amount of rain falling into the receiver 
and flowing into- C fills the latter to a depth greater than the actual 
rainfall in proportion as the area of the receiver is greater than the 
area of the measuring tube. In the standard gages of the Weather 
Bureau the depth of the rainfall, in accordance with this principle, is 
magnified just 10 times. The receiver A has a sleeve d^ figure 1, 
which slips over the tube 6^, and very effectually prevents any loss of 
rainfall. Again, when the rainfall is very heavy the tube G may be 
more than filled. In this case, to still prevent loss, a little opening, 
shown at 6, figure 1, is made in the sleeve d^ just on a level with the 
top of the tube G. 

The excess of rainfall escapes through this opening, and is retained 
in the large overflow attachment B^ and can be measured afterwards, 
as will be described below. The diameter of the overflow attach- 
ment in the latest style gages is now made just 8 inches inside 
diameter. The object of this is to be able to use this portion of 
the instrument as a snow gage, as will be explained hereinafter. 

RAIN GAGE AND SUPPORT. 

The box in which the- gage is shipped to the observer is expressly 
designed as a stand for the instrument, and should be opened at the 
bead, which is fastened by screws. Set the box up as nearly vertical 
as possible at the place selected for the exposure and secure it in 
this position by driving down four stakes alongside, in the manner 
indicated in figure 2. Care must be taken to have the gage in a 
truly vertical position. Slip in the head and lower it to the level 



INSTRUCTIONS TO SPECIAL KIVER AND RAINFALL OBSERVERS. 15 

of the screw holes in the sides of the box about 10 inches from the 
bottom, where the head will be securely fastened with the screws 
taken out in opening the box. The gage can now be placed inside 
and appears as shown in figure 2. 

TO MEASURE RAINFALL AND SNOWFALL. 
RAINFALL. 

The rain-gage measuring stick is graduated into inches and tenths 
of inches. Kemembering that the actual depth of the rainfall is 



Drant Vle;tA>. 



Vertical Section^ 







0/2 3 -^_5 6 7 d 3 ^p ''^^*^ 'f '^ '^ 'L'i. '^ ^9.^L?^^ ^^^if INCHES 

SCALE. 

Fig. 1. — Rain gage. 

magnified 10 times, as explained above, it is plain that if we find 
the water 10 inches deep in the measuring tube the real rainfall 
must haye been only 1 inch deep ; or if the water in the tube is 
only one- tenth inch (or, written as a decimal, 0.1 inch) deep the 
rainfall must have been only one one-hundredth inch (or, written as a 
decimal, 0.01 inch). 

To save observers the trouble of always thinking about the mag- 
nification, and to avoid possible errors in reports, the numbers on 
the graduations of the measuring sticks are not actual inches, but 
have all been divided by 10, and thus represent the actual rainfall. 
Moreover, these numbers are expressed in hundredths of inches of 



16 INSTRUCTIONS TO SPECIAL RIVER AND RAINFALL OBSERVERS. 



rainfall and are written as decimal fractions. Thus the 10-inch 
line is numbered 1.00 (read one and zero hundredths) , which is the 
depth of rainfall in inches corresponding to 10 inches of water in 
the measuring tube ; similarly, the 1-inch line is numbered 0.10 (read 
ten one-hundredths) , which again is the depth of rainfall in inches 
corresponding to 1 inch of water in the tube. 

The depth of the water is measured by inserting the measuring 
stick into the gage through the small hole in the funnel. When the 
stick reaches the bottom of the measuring tube it should be held for 
one or two seconds and then quickly withdrawn and examined to see 

at what division of the graduation the 
top of the wetted portion comes. The 
numbering of this division, as stamped 
on the sticky gives, as has just been 
explained, the actual depth of rainfall, 
and in making out records and reports 
observers should always use the decimal 
expressions. Of course, it will rarely 
happen that the top of the wetted por- 
tion will fall exactly upon one of the 
numbered lines-^it will generally be on 
or near one of the shortest lines. Thus, 
for example, suppose the watermark 
comes to the sixth short line beyond 
the line numbered 0.80, the proper rec- 
ord to make in this case would be 0.86- 
inch rainfall. The number of short 
lines, reckoned from the numbered line 
next lower, are always to be inserted in 
place of the in the standard numbers. 
Observers should always be careful to 
put the stick into the gage so that the 
end at which the numbering begins goes 
to the bottom and the stick passes through the middle of the tube; 
for if the stick is placed near the sides the water is sometimes drawn 
up by capillary action into the narrow space between the stick and 
the tube so as to wet the former entirely too high and give very 
erroneous records. 

After measuring and recording in this way the precipitation found 
in the gage the top should be removed, the measuring tube emptied 
and drained, and the gage put in position again. Observers should be 
careful after emptying the gage to replace the measuring tube so that 
the bottom stands within the ring in the middle of the bottom of the 




Fig. 2. — Rain gage and support. 



INSTKUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 17 

overflow, and in putting on the receiver to see that it passes over the 
measuring tube and rests squarely down upon the overflow. 

When the amount of rain that has fallen more than fills the measur- 
ing tube some care is required to determine the total rainfall. First, 
carefully remove the receiver so as not to spill any of the water in the 
measuring tube, which should be exactly full. If some water has 
been slopped out and the measuring tube is not exactly full, the 
amount of water remaining must be accurately measured with the 
stick as already described. The tube is then lifted out slowly and 
carefully, if full, so as not to spill any of the water into the overflow, 
emptied, and allowed to drain a moment or so. The water remaining 
in the overflow is then poured into the measuring tube, care being 
taken not to lose any, and measured in the usual way. Suppose this 
is found to be 0.47 inch rainfall, then, remembering that the measur- 
ing tube contains just 2 inches, the total rainfall will be 2 inches plus 
0.47 inch =2.47 inches. Or, in case some water was spilled from the 
measuring tube, the 0.47 inch should be simply added to the first 
measured amount to give the total rainfall. 

SNOWFALL. 

During the winter season, especially in those climates where the 
precipitation is nearly all in the form of snow, only the overflow 
attachment will be exposed in the support as a snow gage, removing 
the receiver and measuring tube to the house. These parts can not 
be used for .measuring snow, and even if rain should occur it would 
be very apt to freeze and injure the measuring tube. 

When the overflow collector is unprotected from the wind its catch 
represents the true amount of snow only in the case of precipitation 
during calms or very light winds. On windy occasions the catch is 
often highly inaccurate. The true quantity must be found, if pos- 
sible, by measuring a section of the freshly fallen snow cut out by 
forcing the overflow^ mouth downward, through the layer and then 
slipping a thin board or sheet of metal underneath so as to separate 
and lift up the section of snow thus cut out. 

Assuming that a representative quantity of snow has been obtained 
in the overflow, a measurement may be secured by placing the vessel 
in a warm room until the snow has melted and then measuring the 
water in the measuring tube in the usual way. 

The method just described is objectionable, owing to the time re- 
quired and to the loss of the snow or water by evaporation. The 
following plan is much better : Take the overflow into the room and 
pour into it one measuring tube full of water to the hrim^ preferably 
warm. In cases of deep snowfall more water will be required. This 



18 INSTRUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 

will melt, or at least reduce to a fluid slush, a considerable amount 
of snow. The measuring tube should then be filled to the brim from 
the melted contents of the overflow and emptied, thereby discarding 
a quantity of water equal to that added. The remaining water in 
the overflow, when measured in the tube, then gives the actual depth 
of melted snow. 

In addition to this measurement by the gage a measurement will 
be made of the actual depth in inches of the snow on the ground. 
Select a level place of some extent, where the drifting is least pro- 
nounced, and measure the snow in at least three places. The mean 
of these measurements will give the snowfall, which is to be entered 
in the column of the report headed " Depth of snowfall in inches." 
Whenever it is impracticable to melt the snow as described in the 
preceding paragraph, one-tenth of this mean will give an approxi- 
mate value, in water, for the snow which could not be melted. This 
value must be set down in the proper column of the report in pre- 
cisely the same manner as rainfall or snow melted in the gage. 
After snowfall has once been measured, the same snow should not be 
measured at subsequent observations. Any fresh snow, however, 
should be measured and recorded. 

Observations of rainfall should be made at the time of river ob- 
servations, and the gage should be emptied of all the water it may 
contain as soon as it has been measured. 

If no rain, snow, or hail has fallen during the period of observa- 
tion, make the entry ".00 " in the proper column. If the amount is 
too small to measure, make the entry " Trace " or " T." 

It is particularly important, in the interest of accuracy, that the 
observations be recorded as soon as made and that the daily entries 
be made each day. Even if no rain has fallen, the observer should 
bear in mind that his official record of that fact is very important. 

RIVER GAGES. 

A river stage is the vertical height of the water flowing in a 
stream above or below a definite plane called the zero of the river 
gage. A river gage is a device for determining that height. It is 
very important that the zero of the gage be determined with great 
care. The best plane of reference is the bottom of flowing water in 
the stream. This point can be easily determined when there is a bar 
below the gage, since when the river is at a low stage there will be 
very little or no water flowing over the bar. The depth of water 
over the bar at the lowest point should be ascertained by soundings 
and the zero of the gage made to correspond thereto. In the absence 
of a bar it will be necessary to make a series of cross sections, or 
soundings, at and near the point selected for the gage, with a view of 



INSTRUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 19 

determining the slope of the bottom of the river bed for a short 
distance both above and below that point. 

When a gage is once established and a long record of readings has 
been made, it is not advisable to make any change in zero. In no 
case will the zero of a river gage be changed without the previous 
approval of the central office. The greatest care 'should be taken 
to maintain the absolute stability of all river gages. They should be 
carefully inspected from time to time with a view of discovering any 
possible changes due to settling, deviation from the perpendicular, 
stretching of chains and tapes, etc. 

Bench marks. — For the purpose of ascertaining any changes that 
may occur in the level of the zero of a gage or any of its marks, 
from causes described above, a bench mark should be established 
close by the gage or somewhere in its immediate vicinity. A bench 
mark consists of some accessible, presumably permanent, point or 
surface, the difference in level between which and the zero or some 
other mark on the gage is known by actual leveling between the two. 
When this difference is found to vary it is presumed to indicate a 
corresponding change in the level of the marks of the gage, requir- 
ing either adjustment of the gage or correction of the readings. 
Such a difference will be reported immediately upon its discovery 
to the district center. 

Suggested locations for a bench mark are: The top surface of a 
large stone in the top course of masonry on a bridge pier. Some- 
times a bench mark is located in the top surface of a large stone 
buried in the ground specially for the purpose of establishing a per- 
manent surface. Prominent surfaces in stone buildings are good 
places for permanent bench marks. 

A copper bolt or metal plate set in the stone wall of some public 
building, such as the customhouse, post office, or city hall, is a com- 
mon device for a bench mark in a large city. 

The river gages used by the Weather Bureau are partly shown in 
figures 3, 4, 5, 6, and 7. The design best adapted to any particular 
location will be used in each case. 

The specifications to be followed in procuring bids for the con- 
struction of these gages are as follows: 

SPECIFICATIONS FOR RIVER GAGE SHOWN IN FIGURE 3. 

The river gage will be made of sound pine or oak timber, free from 
knots or shakes, 2 inches in thickness, 12 inches in width, and of such 
a length as to extend, if possible, from 2 or more feet below the zero 
point to about 5 feet above the highest known water. The face of 
the plank upon which the graduations are to be made and the top, 
bottom, and sides will be planed smooth and will receive two coats 



20 INSTRUCTIONS TO SPECIAL EIVERAND RAINFALL OBSERVERS. 



6 



Hf 



€ 



of the best white-lead paint. The face will then be graduated as 
follows : 

Commencing at the point which will correspond to the zero, gradu- 
ate the gage both above and below that point in feet and tenths of 
feet. 

The graduations will be chiseled or burnt into the wood to the 
depth of about one-eighth of an inch and then 
given two coats of the best black paint. The 
marks for whole feet will extend entirely across 
the face of the gage; those for half -feet one-half 
the distance across, beginning on the left side, 
and those for the intermediate graduations one- 
fourth of the distance across, beginning on the left 
side. Whole feet will also be shown by the ap- 
propriate figures, 6 inches in height, on the right 
side of the gage, and so placed that the marks for 
whole feet will exactly bisect the figures. The fig- 
ures will also be chiseled or burnt into the w^ood 
to the depth of about one-eighth of an inch, and 
then given two coats of the best black paint. An 
enameled plate with the legend, "U. S. Weather 
Bureau," will be fastened at the top of the gage. 
These can be obtained on stores requisition on the 
central office. 

Having graduated the gage, select a pile or other 
stationary object on some portion of the levee, 
wharf, or bridge pier where the gage is to be in- 
stalled, lower the gage into the water until its zero 
is exactly at the point selected as the zero of the river 
plane, taking care to keep it in a vertical position, 
then securely fasten it in this position by spikes 
or bolts. 



1-^ 



6 



i-e 



I— /2 
Fig. 3. 



SPECIFICATIONS FOR RIVER GAGE SHOWN IN 
FIGURE 4. 



Procure a piece of pine, cypress, or oak timber 
about 6 by 6 inches, and of sufficient length to 
cover the full range of the river between extreme 
low and high water marks. This timber will be 
placed in the river bank, firmly embedded in the earth, leaving IJ 
inches exposed above the level of the ground. 

To secure this form of gage thoroughly it will be necessary to 
attach it to 4 by 6 or 6 by 6 inch oak, cedar, locust, or fir posts, driven 



INSTKUCTIONS TO SPECIAL EIVEB AND EAINFALL OBSEKVIIRS. 21 

6 feet in the ground, and placed 6 feet apart. The upper edge of 
the gage should be planed smooth, and a strap of iron, ^ by 2 inches 
screwed along the top on the upstream side, and graduated in feet 
and tenths of feet, after being placed in position, taking the point 
which has been selected as the zero of the scale, and locating the 
feet and tenths both above and below that point. The screw holes 
in the strap of iron, except the one near the middle, should be 
slightly elongated and there should be about one-tenth inch of space 
for every 10 feet on length left between the ends where two straps are 
joined so as to provide for the expansion of the iron without buck- 
ling. The graduations for this gage will be the same as for the 
gage shown in figure 3. Especial pains should be taken in graduat- 
ing the gage to see that the distances marked off upon it for each 



4feet 



//hot 













\ < / 

A « I 

\ < / 



Fig. 4. 



foot and its subdivisions correspond exactly to a vertical foot and its 
subdivisions of which it is a measure. This should be done by an 
engineer whenever possible. 

It is also very desirable that this form of gage should have its top 
surface covered with two coats of the best white-lead or zinc paint, 
with the proper figures opposite the footmarks on the iron strap 
in black paint and not less than 4 inches in length. Figures should 
also be burnt in before painting, as permanent markings are thereby 
secured. 

Specifications for an inclined gage of concrete construction should 
invariably be forwarded to the central office for aproval. 

SPECIFICATIONS FOR RIVER GAGE SHOWN IN FIGURE 5. 

Where a stone pier or abutment is available, a very durable gage 
can be made by dressing a face, 12 inches in width, from extreme low 



22 INSTRUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 

water to as far above as may be necessary. The dressed surface 
should be covered with two coats of the best black paint, preferably 
asphaltum, after all holes and indentations in the pier have been 
filled with cement. 




Fig. 5. 

The space, both above and below the point at which the zero will 
be placed, will be graduated with two coats of the best white-lead or 
zinc paint into feet and tenths of feet. Markings for whole feet will 
extend entirely across the gage ; those for half feet one-half the way 
across, beginning on the left side; and those for the intermediate 
graduations one-quarter of the way across, beginning on the left 



INSTRUCTIONS TO SPECIAL RIVER AND RAINFALL OBSERVERS. 



23 



side. All markings will be one-quarter of an inch in width. The 
figures for the whole footmarks will be in white, 5 inches in height, 
and the center of each figure must be over the foot line at the right. 
If the face of the pier is not vertical, care must be taken to see that 
the distance marked off for each foot and its subdivisions correspond 
exactly to a vertical foot and its subdivisions. The amount of the 
slope of the pier should also be reported. 

THE ENAMELED SCALE GAGE. 



This form of gage consists of numerals and graduated slabs or 
sections, which, being screwed upon a supporting timber, form the 
scale of a vertical staff gage. The advan- 
tages of the enameled scale are legibility and 
durability ; it does not tarnish when exposed 
to the weather, and it may be washed off 
when mud accumulates on the lower section. 
The drawing below shows a section of the 
gage and its support. The width of the 
graduated section is 4 inches and of the 
integers 3 inches each ; consequently the sup- 
port must be 11 inches wide. The support 
should consist of 2 by 11 inch plank, prefer- 
ably cypress, dressed on both sides, to be 
given a coat of raw linseed oil and then two 
coats of lampblack and oil. When practi- 
cable, battens of 2 by 4 stuff should be 
attached to the underside of the plank, but 
where the planks must be attached to the 
side of the pier the battens may be omit- 
ted. In making requisition for an enameled 
gage it is necessary to give the range in 
river stages the gage is to cover. The in- 
tegers and graduated sections are attached to the timber support 

by screws. 

CHAIN- AND-WEIGHT RIVER GAGE. 

SHORT BOX PATTERN. 

The box is 2 feet long, 6 inches wide, 8 inches high on the back, 
and 5^ inches on the front. The hole for the down spout is in the 
center of the box, so that the scale may be placed on either side, 
although the scale provided is intended to be placed on the left side 
of the box. The enameled scale is in five sections, each 2^ feet long, 
and is graduated from 2^ feet below to 10 feet above zero. An inch 
board of sufficient length should be attached to the bridge rail in 




Fig. 6. 



24 INSTRUCTIONS TO SPECIAL KIVER AND RAINFALL OBSERVERS. 

order to bring the scale out flush with the slot in the end of the 
gage box. 

The box should be securely fastened by its 8-inch side to the out- 
side of the guard rail, or side of the bridge, the former preferred. 
If it should be necessary, a 2 by 8 inch plank of cypress or hard pine 
will be fastened to the bridge and the gage attached to this. Before 
attaching the box to the bridge the down spout should be screwed 
into the underside of the box so that the hole in the pipe is opposite 
the hole in the back of the box, and the bolt should be put through 
and bolted on the outside. 

In placing the enameled scale, a careful measurement should be 
made from the zero of the scale to the 10-foot mark, to see that it is 
exactly 10 feet. It may be necessary to overlap the sections at the 
5-foot point slightly in order to do this. 

An open pulley is used in order that the chain and weight may 
be taken up into the box after each observation. The weight should 
be laid in the bottom of the box and the chain carefully piled from 
end to end of the box, care being taken not to lay the chain across 
the upper end of the down spout, in order to prevent its being tam- 
pered with. 

When the zero of the river has been established the weight will 
be lowered so that its lower end just touches the zero point. The 
link of the chain directly opposite the zero mark on the scale will 
then have a rivet put into it and flattened on both sides, so that it 
will remain firm. Should it be necessary to record river readings 
beyond the scale limits, the rivet in the chain will be drawn up so 
that it will be exactly opposite the highest footmark on the scale. 
Another rivet will be placed in the link of the chain exactly oppo- 
site the zero mark of the scale and readings taken, using this second 
rivet as a base. A third rivet can also be added, if necessary. In 
recording readings which are beyond the scale limits, the second or 
third rivet will be used as a zero mark instead of the first, and 
there will be added to the observed reading the distance between the 
rivets — 10, 20, 30 feet, etc., as the case may be. The weight is pro- 
vided with an adjustable eyebolt, by which any slight error in the 
placing of the rivet may be corrected. The nut on the bolt should 
then be firmly tightened to prevent any change. If left loose, the 
weight is liable to get out of adjustment and thus cause an error in 
the readings. 

In making requisition for gages, officials in charge of river dis- 
tricts will state the length of chain required. 

The box attachments are sent complete, and the only materials 
to be supplied at the station are the bolts or screws for attaching the 



INSTRUCTIONS TO SPECIAL EIVEE AND RAINFALL OBSERVERS. 25 

box to the bridge and a board and plank when needed. Figure 7 
shows the chain and weight gage in place. 

DESCRIPTION OF THE MOTT RIVER GAGE. 

Box. — The gage box and doors are constructed of sand-dried oak 
lumber dressed on all surfaces, |-inch stock, and inside dimensions as 
follows: Height, 18 inches; width, 18 inches; depth, TJ inches. 

Doors. — The box has two doors secured vvdth extension hinges in 
such manner as to permit the doors to swing back against the sides of 
the galvanized-iron bos. The entire outside surface of the box, ex- 
cepting the bottom, and including the doors, is covered with No. 24 
galvanized iron. The joints of the galvanized-iron cover are lapped 
and soldered, making the cover water-tight. The galvanized-iron 
cover of the box is painted with two coats of dark-green mineral 
paint, with a label on the doors of the box bearing the words " Prop- 
erty United States Weather Bureau. Penalty for Interference." 

Lock. — The box is fitted with a brass mortise lock, using the same 
key as is used in the standard padlock for the chain and w^eight gages 
of the United States Weather Bureau and United States Geological 
Survey. 

Mechanism. — The box is fitted with a tape reel consisting of an 
aluminum brake wheel and a brass spider, mounted on a turned cast- 
iron standard and fitted with a wooden handle. A leather brake strap 
and suitable levers for releasing the brake are provided. The brake 
strap is attached to a brass coil spring of sufficient strength to hold 
the weight and tape in any position. An iron guide wheel running 
on a turned axle, secured in the box by a cast-iron standard, is also 
provided. 

Tape and gage. — The tape is made of phosphor bronze, one-fiftieth 
inch in thickness and one- fourth inch in width. It is nickeled 
throughout, excepting the relief in which the figures are etched, 
which is plain. The tape, accurately subdivided to feet, with foot 
marks numbered consecutively between such limits as may be neces- 
sary, is furnished with each gage. A 1-foot scale divided into 100 
parts, and having every fifth division mark suitably numbered, is 
placed in the box so as to stand cornerwise back of the tape in a ver- 
tical position. This scale is made of No. 16 gage iron, enameled in 
black and white with six coats of enamel, and is attached to an iron 
bar which projects upward through the top of the box, the projecting 
end being covered by a cast-iron cap or cover attached to the box 
by screws, the object being to provide a suitable bench or reference 
mark outside the box. 

The 1-foot scale is adjustable vertically. A standard weight is 
provided with each gage, together with a clip and wire for attaching 
the same to the tape. 



26 INSTRUCTIONS TO SPECIAL EIVEK AND EAINFALL OBSEKVEES. 

Miscellaneous. — Each gage contains a covered compartment for the 
observer's record card, etc., instructions for erecting a gage in various 
positions, for attaching the weight, checking the gage datum, and 
operating the gage. 

A rectangular wooden down spout, 16 inches in length, with screw 
for attaching the same, is provided with each gage. 

Each gage is also provided with a screw driver and a f-inch twist 
drill for use in erecting the gage. 

Operation. — Release brake and slowly unwind tape until weight 
reaches water. Do not run tape all out without holding reel handle. 
Brake will hold reel in position, and observer can stand to one side to 
see that tip of weight just touches water. Read number of whole feet 
on bronze tape and tenths of a foot on enameled scale. The figure on 
the tape standing opposite some part of the 1-foot scale gives the 
whole feet ; the number of tenths and hundredths on the 1-foot scale 
opposite the index of the number on the tape gives the decimal or 
fractional portion of the gage reading. 

For example, if the number 7 on the tape stands opposite 60 on the 
enameled scale, the gage reading would be 7.6 feet. If the number 
—2 feet (2 feet below zero) is opposite 74 on the enameled scale the 
reading is —2.26, recorded —2.3 feet (2.3 feet below zero)— 1 foot 
—0.74 foot =0.26 foot, for the fractional part — the complete reading 
being —2.26. When the reading is below zero the number on the 
enameled scale opposite the figure on the tape will be subtracted 
from the number of whole feet recorded. 

Erection. — The gage may be bolted to the handrail of a bridge, if 
not liable to interference, one side being fastened to tiebars that 
extend down to the floor of the bridge. It may also be secured to a 
platform extending beyond the handrail, the bottom of the box being 
on a level with the top of the rail. When there is no handrail, as on 
most railroad bridges, the gage may be bolted or secured to vertical 
bridge members, or it may stand on horizontal bridge chords, or be 
attached to two sleepers at their ends. In all cases room must be 
provided for the unobstructed movement of the weight. 

A small supply of Mott gages, ready for installation, remains on 
hand at the central office and bids for installation will be necessary. 
These gages will be supplied where suitable for the local needs, but 
as a rule preference will be given to the chain and weight gage 
described on previous pages. 

In each instance the exact distance from the zero stage of the water 
to the bottom of the gage box when in position must be furnished. 



INSTRUCTIONS TO SPECIAL EIVER AND RAINFALL OBSERVERS. 27 
TABLE FOR CONVERTING INCHES INTO TENTHS OF A FOOT. 

If the river gage is graduated in feet and inches, the inches will 
be converted into tenths of a foot hj the following table before 
telegraphing : 

1 ineii of water equals one-tenth (0.1) of a foot. 

2 inches of water equal two-tenths (0.2) of a foot. 

3 inches of water equal two-tenths (0.2) of a foot. 

4 inches of water equal three-tenths (0.3) of a foot. 

5 inches of water equal four-tenths (0.4) of a foot. 

6 inches of water equal five-tenths (0.5) of a foot. 

7 inches of water equal six-tenths (0.6) of a foot. 

8 inches of water equal seven- tenths (0.7) of a foot. 

9 inches of water equal eight-tenths (0.8) of a foot. 

10 inches of water equal eight-tenths (0.8) of a foot. 

11 inches of water equal nine-tenths (0.9) of a foot. 

O 




n,K^,('Y Of" CONGRESS 

019 953 643 6 



